Republican presidential hopeful John McCain named the youngest and first female governor of Alaska, Sarah Palin, as his running mate today.

In an election which will be about change, so-called "hockey mum" Ms Palin is virtually unknown outside Alaska, where she has a reputation for government reform and an approval rating higher than 80 per cent.

The 44-year-old former runner-up of the 1984 Miss Alaska beauty pageant will be the second female vice-presidential nominee of a major party, following Geraldine Ferraro as Democratic nominee in 1984.

Democratic nominee Barack Obama is making an aggressive play for the traditional Republican stronghold of Alaska and its three electoral votes, and polls show the race is close.

Whoever wins, America will either have its first black president or its first female vice president in history.

At a raucous rally in the swing state of Ohio, Mr McCain said he made his pick after looking for a political partner "who can best help me shake up Washington and make it start working again for the people who are counting on us".

He said Ms Palin was "exactly who I need" and "exactly who this country needs to help us fight the same old Washington politics of me first and country second".

The decision to pick a woman for his ticket may help Mr McCain attract some of Hillary Clinton's former supporters who have been disillusioned with the Democrats after a prolonged and often-bitter primary election battle against Mr Obama.

To huge cheers, Ms Palin said she wanted to honour the former first lady who had shown "such determination and grace in her presidential campaign".

"But it turns out the women of America aren't finished yet and we can shatter that glass ceiling once and for all," she said.

"If you want change in Washington, if you hope for a better America, then we're asking for your votes on the fourth of November."

Ms Palin also borrowed Mrs Clinton's remark that the former first lady had put 18 million cracks in the glass ceiling for women, a reference to the 18 million votes the 60-year-old New York Senator won in her unsuccessful presidential campaign.

One former Clinton supporter, lifelong Democrat Debra Bartoshevich, has already defected to Mr McCain and has featured in an attack advert encouraging others to do the same.

Taking to the stage with her family watching, mother-of-five Ms Palin said she never set out to become a vice presidential nominee and was instead a "hockey mum".

But after joining her children's Parent Teacher Association, she became involved in her local council, was elected mayor of her home town, and said her agenda was "to put the people first".

"It's always safer in politics to avoid risk, to go along with the status quo, but I didn't get into government to do the safe and easy things," she said.

"Politics isn't just a game of competing interests and clashing parties."

She said she wanted to serve America "to challenge the status quo and to serve the common good".

Mr McCain reportedly chose Ms Palin as his vice presidential nominee yesterday, but the decision has been shrouded in secrecy.

Speculation only moved to mother-of-five Ms Palin, who, like Mr McCain calls herself a maverick and was considered an outside bet, after airport officials confirmed a private plane flew from Alaska into Middletown Regional Airport in Butler County, near Cincinnati, Ohio, ahead of the official announcement in the state.

Many US political pundits ruled her out because her office remains under investigation over the dismissal of a commissioner who refused to fire her brother-in-law.

She is a pro-life devout Christian, a fiscal and social conservative and holds a lifetime membership with the National Rifle Association.

She rose to attention in Alaska after blowing the whistle on ethical violations by state Republican Party leaders and was elected in 2006 after beating the incumbent Republican governor in the primary and a former Democratic Alaskan governor in the general election.

On 18 April, Ms Palin, gave birth to her second son, Trig Paxson Van Palin, who has Down's syndrome, after she refused to let the results of antenatal genetic testing change her decision to have a baby.

Born in Sandpoint, Idaho, on 11 February 1964, Ms Palin moved to Alaska with her family as an infant.

In the 1980s, she earned the nickname "Sarah Barracuda" for the intensity of her play as captain for the Wasilla High School Warriors basketball team in Wasilla, Alaska.

In 1984, Ms Palin came second in the Miss Alaska beauty pageant after winning the Miss Wasilla contest earlier that year, winning a scholarship to help pay her way through college. She also won the Miss Congeniality award.

She has a journalism degree from the University of Idaho, where she also minored in politics.

Ms Palin has also admitted using marijuana when it was legal in Alaska, but has said she did not like it.

Her husband, Todd, is a Native Yup'ik Eskimo who works for BP outside the fishing season and is a champion snowmobiler, winning the 2,000-mile "Iron Dog" race four times.

The couple, who are celebrating their 20th wedding anniversary today, eloped after she finished college and reportedly recruited two residents from a nearby elderly care home when the pair realised they needed witnesses for the civil ceremony.

Their eldest son, Track, 18 at the time, joined the US Army on 11 September last year and will be deployed to Iraq next month.

She also has three daughters - Bristol, 17, Willow, 13, and Piper, seven.

Minnesota governor Tim Pawlenty, former Massachusetts governor Mitt Romney, former Pennsylvania governor Tom Ridge, and Democrat-turned-independent Joe Lieberman were among others thought to be considered for the job.